1. Technical Field
The present invention relates to a method of manufacturing an optical filter, an analytical instrument, and an optical apparatus.
2. Related Art
There has been proposed a method of bonding two base substances to each other efficiently under low temperature, firmly with high dimensional accuracy, without using an adhesive or solid-state bonding, irrespectively of the material thereof (Japanese Patent No. 4,337,935 (Document 1)). According to this method, the bonding films provided respectively to the two base substances are activated with the activation energy to thereby be bonded to each other.
This bonding method can be used in various types of applications including the interference filter having a variable transmission wavelength as one example (JP-A-11-142752 (Document 2)). As shown in FIG. 1 of Document 2, there are provided a pair of substrates held in parallel to each other, and a pair of reflecting films formed on the pair of substrates so as to be opposed to each other and have a gap with a constant distance therebetween. The light beam entering the gap between the pair of reflecting films is multiply reflected on the same principle as a Fabry-Perot interferometer, and the light component in the wavelength band other than a specific wavelength band is canceled by interference while only the light component in the specific wavelength band is transmitted. By making the gap between the pair of reflecting films variable, the interference filter functions as a band-pass filter, and is called an etalon.
The pair of reflecting films can be formed of, for example, dielectric multilayer films shown in Document 2, or metal films assuring high reflectance.
It is expected that when manufacturing the interference filter according to Document 2 or JP-A-2009-134028 the pair of substrates are bonded to each other using the technology according to Document 1.
Incidentally, in the bonding method according to Document 1, bonding can be performed by activating the bonding film with ozone or ultraviolet radiation. It has turned up that in the activation process of the bonding film a pair of reflecting films formed of metal films or dielectric multilayer films might be damaged to be changed in quality or deteriorated, and thus the reflectance thereof might be degraded.